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Simplify compact_hash_table implementation

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Instead of a separate implementation for find/insert, use just one that
can do both. This reduces the code size and simplifies code coverage;
the resulting code is close to what we had in terms of performance and
since hash table is a fall back should not affect any real workloads.
This commit is contained in:
Arseny Kapoulkine 2017-02-23 00:23:01 +03:00
parent 03e4b8de92
commit 8ce4592e15
1 changed files with 38 additions and 45 deletions
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83
src/pugixml.cpp
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@ -274,61 +274,31 @@ PUGI__NS_BEGIN
}
}
void** find(const void* key)
void* find(const void* key)
{
assert(key);
if (_capacity == 0) return 0;
size_t hashmod = _capacity - 1;
size_t bucket = hash(key) & hashmod;
item_t* item = get_item(key);
assert(item);
assert(item->key == key || (item->key == 0 && item->value == 0));
for (size_t probe = 0; probe <= hashmod; ++probe)
{
item_t& probe_item = _items[bucket];
if (probe_item.key == key)
return &probe_item.value;
if (probe_item.key == 0)
return 0;
// hash collision, quadratic probing
bucket = (bucket + probe + 1) & hashmod;
}
assert(false && "Hash table is full");
return 0;
return item->value;
}
void** insert(const void* key)
void insert(const void* key, void* value)
{
assert(key);
assert(_capacity != 0 && _count < _capacity - _capacity / 4);
size_t hashmod = _capacity - 1;
size_t bucket = hash(key) & hashmod;
item_t* item = get_item(key);
assert(item);
for (size_t probe = 0; probe <= hashmod; ++probe)
if (item->key == 0)
{
item_t& probe_item = _items[bucket];
if (probe_item.key == 0)
{
probe_item.key = key;
_count++;
return &probe_item.value;
}
if (probe_item.key == key)
return &probe_item.value;
// hash collision, quadratic probing
bucket = (bucket + probe + 1) & hashmod;
_count++;
item->key = key;
}
assert(false && "Hash table is full");
return 0;
item->value = value;
}
bool reserve()
@ -353,6 +323,29 @@ PUGI__NS_BEGIN
bool rehash();
item_t* get_item(const void* key)
{
assert(key);
assert(_capacity > 0);
size_t hashmod = _capacity - 1;
size_t bucket = hash(key) & hashmod;
for (size_t probe = 0; probe <= hashmod; ++probe)
{
item_t& probe_item = _items[bucket];
if (probe_item.key == key || probe_item.key == 0)
return &probe_item;
// hash collision, quadratic probing
bucket = (bucket + probe + 1) & hashmod;
}
assert(false && "Hash table is full");
return 0;
}
static unsigned int hash(const void* key)
{
unsigned int h = static_cast<unsigned int>(reinterpret_cast<uintptr_t>(key));
@ -381,7 +374,7 @@ PUGI__NS_BEGIN
for (size_t i = 0; i < _capacity; ++i)
if (_items[i].key)
*rt.insert(_items[i].key) = _items[i].value;
rt.insert(_items[i].key, _items[i].value);
if (_items)
xml_memory::deallocate(_items);
@ -773,12 +766,12 @@ PUGI__NS_BEGIN
template <int header_offset, typename T> PUGI__FN_NO_INLINE T* compact_get_value(const void* object)
{
return static_cast<T*>(*compact_get_page(object, header_offset)->allocator->_hash->find(object));
return static_cast<T*>(compact_get_page(object, header_offset)->allocator->_hash->find(object));
}
template <int header_offset, typename T> PUGI__FN_NO_INLINE void compact_set_value(const void* object, T* value)
{
*compact_get_page(object, header_offset)->allocator->_hash->insert(object) = value;
compact_get_page(object, header_offset)->allocator->_hash->insert(object, value);
}
template <typename T, int header_offset, int start = -126> class compact_pointer